I got Part A incorrect, so I need Part B to be solved

Ten cavemen with a remaining average life expectancy of 10 years use a path from their cave to a spring some distance away. The path is not easily traveled due to 100 large stones that could be removed. The annual benefit to each individual if the stones were removed is $8.75. Each stone can be removed at a cost of $2.25. The interest rate is 2%. Click here to access the TVM Factor Table Calculator Part a X Your answer is incorrect. Compute the benefit/cost ratio for the individual if he alone removed the 100 stones. 0.79 Carry all interim calculations to 5 decimal places and then round your final answer to 2 decimal places. The tolerance is +0.02. Attempts: 3 of 3 used Part b Your answer is incorrect. Compute the benefit/cost ratio for the individual if the task was undertaken collectively, with each individual removing 10 stones. Carry all interim calculations to 5 decimal places and then round your final answer to 2 decimal places. The tolerance is tnn